440 



COMPARATIVE MORPHOLOGY OF FUNGI 



This grows epiphytically on shrubs and tree trunks, forming blue-green 

 brackets, with lighter margins. At the beginning of the period of fructi- 

 fication, they develop on the lower side numerous spreading hyphal 

 fascicles, whose branches terminate in four-spored basidia (Fig. 283, 2). 

 The fungus appears in Nature without the alga and forms brackets, in 

 living with the alga, it attains much larger dimensions, and is able to 

 thrive in places where it could not grow alone, e.g., in the forest crown. 

 With another alga, Scytonema, it forms another lichen which is placed in 

 Dichonema (Dictyonema) in systematic literature (Fig. 284, 1). Under 

 certain conditions in this association, not the fungal hyphae, but the 

 alga determines the form of the lichen, so that this lichen is modified to 



Fig. 284. — Cora pavonia. 1. Dichonema sericeum form; thallus on twig. 2. Lauda- 

 tea caespitosa form; portion of bark and leaves covered with lichen thallus which bears 

 parallel white hymenia. ( X H ; after Johow, 1884.) 



a special Laudatea form (Johow, 1884, Moller, 1893). The lichens, as 

 those here, in which the fungus component is a member of the Basidio- 

 mycetes, are classed together as Hymenolichenes. 



Cyphellaceae. — This family connects directly to the Corticiaceae, 

 especially to the Corticium stage. By a strongly hyponastic growth, 

 the fructification develops to a pezizoid cup which contains the 

 hymenium in the interior. Some of the genera are distinguished by a 

 gelatinization of the hyphal membranes. 



In the simpler genera, as in Aleurodiscus (fructifications waxy, 

 leathery or fleshy) and Cytidia (fructifications gelatinous), the fructifica- 

 tions are resupinate crusts in youth. During the course of development 

 the edges are reflexed and the fructification becomes patelliform (Stork, 

 1920). In Aleurodiscus, the hymenia contain peculiar paraphysoid 

 structures; these are thin- walled and smooth, swollen toward the top, 

 and moniform (pseudophyses, Fig. 285, 1); or they may be thin- or 

 thick-walled and covered throughout or in spots with crowded, gener- 



